leetcode-java/src/IsomorphicStrings205.java at master · fluency03/leetcode-java · GitHub

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/**
 * Given two strings s and t, determine if they are isomorphic.
 *
 * Two strings are isomorphic if the characters in s can be replaced to get t.
 *
 * All occurrences of a character must be replaced with another character
 * while preserving the order of characters. No two characters may map to the
 * same character but a character may map to itself.
 *
 * Example 1:
 * Input: s = "egg", t = "add"
 * Output: true
 *
 * Example 2:
 * Input: s = "foo", t = "bar"
 * Output: false
 *
 * Example 3:
 * Input: s = "paper", t = "title"
 * Output: true
 *
 * Note:
 * You may assume both s and t have the same length.
 */

publicclassIsomorphicStrings205 {
publicbooleanisIsomorphic(Strings, Stringt) {
if (s == null && t == null) returntrue;
if (s == null || t == null || s.length() != t.length()) returnfalse;

intN = s.length();
char[] charS = s.toCharArray();
char[] charT = t.toCharArray();
Map<Character, Character> map = newHashMap<>();
for (inti=0; i<N; i++) {
if (map.containsKey(charS[i])) {
if (map.get(charS[i]) != charT[i]) returnfalse;
 } else {
if (map.values().contains(charT[i])) {
returnfalse;
 } else {
map.put(charS[i], charT[i]);
 }
 }
 }
returntrue;
 }


publicbooleanisIsomorphic2(Strings1, Strings2) {
int[] m = newint[512];
for (inti = 0; i < s1.length(); i++) {
if (m[s1.charAt(i)] != m[s2.charAt(i)+256]) returnfalse;
m[s1.charAt(i)] = m[s2.charAt(i)+256] = i+1;
 }
returntrue;
 }


publicbooleanisIsomorphic3(StringsString, StringtString) {
char[] s = sString.toCharArray();
char[] t = tString.toCharArray();

intlength = s.length;
if(length != t.length) returnfalse;

char[] sm = newchar[256];
char[] tm = newchar[256];

for(inti=0; i<length; i++){
charsc = s[i];
chartc = t[i];
if(sm[sc] == 0 && tm[tc] == 0){
sm[sc] = tc;
tm[tc] = sc;
 }else{
if(sm[sc] != tc || tm[tc] != sc){
returnfalse;
 }
 }
 }
returntrue;
 }


publicbooleanisIsomorphic4(StringsString, StringtString) {
returnencode(sString.toCharArray()) == encode(tString.toCharArray());
 }

privateintencode(char[] chars) {
int[] map = newint[256];
intres = 0;
intid = 1;
for (inti=1; i<=chars.length; i++) {
charch = chars[i-1];
if (map[ch] == 0) {
map[ch] = id;
id++;
 }
res += map[ch] * i;
 }
returnres;
 }

}